I've done a few bustles for people with RTW dresses and there were always 3 button loops to evenly distribute the fabric. Most were fabric covered. I would put them under the peplum and do something decorative with the train to hide the loops.

How heavy is this going to make the dress? My daughter got married last month and decided against a bustle because she said that it made her feel as though she was going to fall over backwards. Maybe a wrist loop at the hem is better being Satin is so heavy. Just a thought. Colleen

Most trains have an odd number of pick-up points, the same number on each side of the center, and one in the center.

It is quite common to have five or seven bustle loops on a heavy train, and I've done trains with more.

As far as bustle loop material, my personal favorite was 1/8 inch ribbon, tied to a backer button underneath. make sure the loops aren't too big; that could be part of the reason they keep coming off. You neen't worry about them showing.
I worked at David's bridal this past summer: the bustle loops were stitched to the dress through all layers (this was the French bustles) and they really don't show.

But it sounds as if you definately need more than two pick-up points.